>> A few years ago I had a 150 mW white LED formally evaluated by its
>> manufacturer. This is a very low power level by most standards for power
>> white LEDs. To my surprise it=A0 constituted a eye hazard at the blue en=
d of
> . th?e spectrum when assessed to the relevant standard. While in this cas=
e the
>> chances of anyone staring into the beam from the minimum distance for lo=
ng
>> enough was vanishingly small, in other situations and with LEDs in the 1
>> Watt + class, real hazards may exist.

> I think you are right. I have noticed some of the=A0 white LED=A0 have hi=
gh=A0
>=A0outt below what most people are capable of seeing. I was using a laser=
=A0
>=A0power meter to measure the output of different LED and found some LED=
=A0
>=A0that appeared to have a higher output on a meter but didn't appear=A0
>=A0brighter to my eyes, some seemed dimmer.
>The only thing that made sense to me was that they were outputting more=A0
> light in the non-visible spectrum . I have also seen white LED that are=
=A0
> capable of being used for exposing UV film on PC boards so those LED=A0
>=A0have to be outputting some UV as well.


They=A0definitely=A0put out UV. I visited a salt water aquarium shop and I =
commented on the=A0fluorescence of the corals and some fish. I asked what t=
hey were using for "black light"=A0and was told they just used a combinatio=
n of blue and white LEDs. Later the facility I work at got one of their=A0a=
quariums complete with light source and I was able to get a close look and =
confirm--just blue and white LEDs.

Roger
--=20
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